April 9, 1998 CfA Colloquium


Title: Very Massive Black Holes in the Centers of Nearby Galaxies

Speaker: Doug Richstone

Abstract: A population of massive black holes in the present universe is predicted by the luminosity function of quasars in the z >~ 2 universe. We believe members of this population have been discovered and that at least the upper end of its mass function can be characterized. We review the evidence for massive dark objects in the centers of ~15 normal galaxies. The numbers and masses of these objects are consistent with our expectations for the population of fossil quasars. The masses of these objects crudely correlate with the mass of the spheroid of its host galaxy. We have devised a technique to estimate the frequency of these objects, including data from nondetections, in an unbiased way. An analysis of ~25 objects suggests that approximately all galaxies host massive black holes. If this is the case, these objects must play a major role in the formation and evolution of galaxies.

Reference for students: "The Demography of Massive Dark Objects in Galactic Centers," astro-ph 9708072